We've been writing a lot lately about the role of philanthropy in influencing public policy, with examples of this popping up often in recent months—like the victorious battle for same-sex marriage, the mounting success of the "war on coal," and the new overtime rule that the Obama administration recently proposed.

In regard to that overtime rule, we wrote about the National Employment Law Project, and all it has done to draw attention to weak and outdated labor regulations. NELP, we noted, has received $15 million in funding from the Ford Foundation since 2009.

The Economic Policy Institute is another think tank that helped shift policy on overtime. But, more than that, EPI has been battling for years to move the issue of stagnant wages to the top of the national agenda—long making the point that while productivity has climbed steadily since the 1970s, most American workers haven't enjoyed the fruits those gains.

While EPI is often thought of as a "labor-backed" think tank, its funding base is pretty diverse. From 2010 to 2012, a majority of its funding (about 60 percent) was in the form of foundation grants, while another quarter or so came from labor unions. EPI also receives support from individuals, corporations, and other organizations. Its budget in 2013 was $6.2 million.

Many of EPI's funders have stuck with it for years. Now, finally, it seems that EPI's moment has arrived. In her first major policy address as a presidential candidate, Hillary Clinton put the goal of raising incomes at the center of her campaign, and Republicans are also addressing inequality in a new way. Meanwhile, a new labor movement has gained steam and scored successes with an urgent call for higher wages.

Then, too, there's the proposed new rule on overtime pay, a cause that EPI has been fighting for since, well, forever.

In research, congressional testimony, and op-eds, EPI called on the president to raise the salary threshold above which workers are ineligible for guaranteed overtime pay—from $23,660 per year, where it has been stalled for decades, up to $51,168 per year, a number only a few hundred dollars more than what the Obama administration has proposed of $50,440 for 2016. If the new rule can survive challenges, it will affect an estimated 6.1 million workers.

Another drum EPI has been banging forever, as mentioned, is the growing gap between productivity and wages—noting that since 1979, productivity has grown eight times faster than median worker pay.* No think tank has pushed this elementary critique of an unfair economy harder or longer than EPI, and lately that point has broken through at a new level, with both President Obama and Hillary Clinton calling attention to the problem in recent years.

Obama, for example, used EPI research when he highlighted stagnant wages in his 2014 State of the Union address. Later that year, EPI launched Raising America’s Pay, a multi-year research and education initiative to make wage growth a national economic policy priority. U.S. Secretary of Labor Thomas Perez presided over the launch of the initiative, which shovels out data to support an ever widening battle on wages and incomes that extends from McDonald's parking lots to city halls and the upper reaches of the federal government.

As for EPI's funders, the Ford Foundation has been a big one, giving it $3.56 million since 2010. The Annie E. Casey Foundation has made 22 grants to EPI since 2003, many of which were focused around policy analysis for low-income families. EPI has also received a slew of grants over the past 12 years from the Open Society Foundations, the Rockefeller Foundation, and the Public Welfare Foundation. Smaller progressive foundations have also backed the institute. For example, EPI received $160,000 from the Bauman Foundation for general operating support in 2014, one of six grants received from Bauman since 2003.

As we said, funders have stuck with EPI for years, even when its ideas were decidedly out of fashion. This is yet another counterpoint to the myth that philanthropy is filled with fickle funders who flit from fad to fad. We see evidence to the contrary all the time, and EPI is just one of many think tanks that's been able to count on a stable of recurring funders for many years.

One lesson here for other nonprofits is that it pays to be super-good at what you do, whatever the fashion of the moment. With a roster of Ph.D. economists, including president Larry Mishel, EPI has long been respected as the premier research shop focused squarely on U.S. workers, and funders have recognized that.